Capacitance Flashcards
Describe a basic capacitor
Two conducting elements separated by an insulating material (dielectric)
How does a capacitor Charge up? (6)
Electrons flow from negative plate in the battery to the positive plate (opposite to current)
Electrons accumulate on one of the sides of the capacitor, this causes negative charge to build on that plate
The negatively charged plate repels electrons original present in the metal of the adjacent plate around the circuit
This creates a flow of charge
Meaning the adjacent plate becomes positively charged
The oppositely charged plates store electric potential energy which increases over time as the potential difference between the plates increase until a certain point
What is Capacitance?
Amount of charge that can be stored by a capacitor per unit voltage across its plates
Q=CV
Q in coulombs V in volts and C in Farads
Why is the formula Q =CV not a good representation and suggest a better formula.
How do you calculate the Capactiance of a Capactior?
What is Dielectric Permitivity?
Measure of the ability of a material to establish an electric field
What is a Dielectric Constant? (relative permittivity)
Whats the formula?
Ratio of the absolute permittivity of a material to that of a vacuum
What is Magnetic Permeability?
Measure of the ability of a material to conduct magnetic flux
measure the degree to which a magnetic field can penetrate through a material.
How do you calculate the speed of light with absolute permittivity and magnetic permeability
Explain how to capacitors store energy?
By establishing an electric field across the dielectric
How do you derive and what are the 3 equations that describe the Energy stored across a capacitor
What is a Step Response?
Change from one DC voltage to another
Derive the Non-Homogenous ordinary differential equation that once solved is the equation that describes the voltage across a capacitor while charging
Whats the Equation that describes the voltage across a capacitor while charging
Whats the Equation that describes the voltage across a capacitor while discharging
Derive the First order homogenous ordinary differential equation that once solved is the equation that describes the voltage across a capacitor while discharging
Work out Vc(t) in terms of Vs for a capacitor charging and discharging
